Ventilator-associated pneumonia after heart surgery:: A prospective analysis and the value of surveillance

Objective; To determine the frequency, etiology, and risk factors of ventilator-associated pneumonia (VAP) and purulent tracheobronchitis (TBX) in patients who have undergone heart surgery. To study the predictive role of systematic surveillance cultures. Design: Prospective study. Setting: Heart surgery intensive care unit. Patients: Intubated heart surgical patients. Interventions: Systematic tracheal aspirate and protected brush catheter cultures of all intubated patients. Measurements and Main Results: Studied were the frequency of lower respiratory tract infection in ventilated patients and the role of surveillance cultures. The frequency of VAP was 7.87% (34.5 per 1,000 days of mechanical ventilation), and the criteria for purulent tracheobronchitis was fulfilled by 8.15% of patients (31.13 per 1,000 days of mechanical ventilation). After multivariate analysis, the variables independently associated with the development of respiratory tract infection were central nervous system disorder (relative risk [RR] = 4.7), ulcer disease (RR = 3.6), New York Heart Association score greater than or equal to3 (RR = 4), need for mechanical circulatory support (RR = 6.8), duration of mechanical ventilation >96 hrs (RR = 12.3), and reintubation (RR = 63.7). Mortality in our study was as follows: VAP patients, 57.1%; purulent tracheobronchitis patients, 20.7%; colonized patients, 11.5%; and noncolonized patients, 1.6%. Regular surveillance cultures were taken from all ventilated patients to assess the anticipative value of the cultures in predicting respiratory tract infection. A total of 1,626 respiratory surveillance samples were obtained. Surveillance cultures effectively predicted only one episode of VAP and one of tracheobronchitis. Conclusions: Patients undergoing heart surgery have a high frequency of VAP. VAP is associated with a poor prognosis. In this study, surveillance cultures failed as an anticipative diagnostic method.